1. Field of the Invention
The present invention relates to an apparatus for automatically cleaning disks, such as semiconductor wafer workpieces which are in the shape of a thin circular disk.
2. Description of the Prior Art
In the semiconductor device manufacturing art, impurities adhering to the surfaces of the semiconductor wafers are known to adversely influence the properties of the resulting semiconductor devices.
Therefore, a cleaning step is included in the semiconductor wafer manufacturing process. In the cleaning step, the wafers are cleaned by various methods which are classified broadly into two groups: mechanical cleaning methods and chemical cleaning methods.
The mechanical cleaning methods include the brushing method wherein the impurities adhering to the wafer surfaces are directly brushed off by means of appropriate brushes, the flushing method wherein the impurities are removed from the wafer surfaces as pressurized fluid from an injection nozzle is applied to the wafer locally or entirely, the ultrasonic cleaning method wherein the wafers are submerged in a liquid and the impurities are vibrated to detach from the wafer surfaces as ultrasonic waves are applied to the wafers.
The chemical cleaning methods include the methods wherein the impurities adhering to the surfaces of the wafers are removed as they are chemically dissolved by various chemicals and enzymes. There are other cases wherein a chemical cleaning method is combined with a mechanical cleaning method.
When treated with any wet cleaning method described above, the wafers can well get rid of the impurities adhering to them. However, as the wafers thus cleaned are removed from the cleaning liquid and brought to the place of a next processing step, the remnant of the cleaning liquid wetting the wafer surfaces evaporates leaving the impurities acquired from the wafers deposited again on the wafers. Further, the impurities in the air also tend to adhere to the wafers.
Various proposals have been made relating to methods as well as apparatuses for cleaning the wafers (e.g., Japanese Patent Publication No. 52-34859 and Japanese Patent Publication No. 60-36099); however, no apparatus has been proposed which is capable of conducting a series of operations in a full automatic manner, starting with feeding of wafers, cleaning them, and recovering them in the end. The fact is that the entire series of the operations were conducted manually so that they required a tremendous amount of time and labor, and therefore improvement of operation efficiency and labor and cost saving have been earnestly desired.